Specializations and polyphagy of Plebejus argus (Lepidoptera: Lycaenidae) in North Wales

Abstract. 1. The polyphagous butterfly, Plebejus argus L., was found to have specialized requirements: eggs are laid along vegetation/bare ground margins, larvae specialize on tender meristematic and reproductive growth, larvae and pupae are tended by Lasius ants, and warm microclimates are favoured.
2. These requirements are met in early successional habitats within several bio topes. These habitats are locally distributed, as is P. argus.
3. Populations on limestone, heathland and mossland biotopes did not differ greatly in ecologies. Given a choice of foodplants in captivity, larvae from heathland and limestone did show slight differences in preference, selecting some of the hostplants they normally encounter in the wild. Regardless of biotope, all these larvae were plant taxa generalists (on three plant families), but specialists on plant parts.
4. The decline of P. argus in Britain is attributed to loss of biotopes and to declining traditional management of them. Fewer habitats are available, and the distances between them are greater than formerly. As some of these habitats are short lived, and P. argus rarely flies far, the butterfly's decline is a compound effect of reduced areas of habitat and inability to colonize them.